Distribution of quantum dots in the internal organs of experimental animals using different injection sites

Distribution of Quantum Dots in the Internal Organs of Experimental Animals Using Different Injection Sites Quantum dots are semiconductor nanoparticles that have unique optical properties such as broad-range excitation, size tunable narrow emission spectra and high photostability. These optical properties proved useful in a wide range of applications: cell sorting and tracking, in vivo imaging and diagnostics. In order to use quantum dots successfully in biology and medicine it is important to fully define factors of distribution of these nanoparticles in an organism. The purpose of this research is to define how distribution of quantum dots in a mice depends on an injection site. In this research quantum dots (CdSe/ZnS-mPEG (655nm)) were injected into a muscle, intravenously into a tail, and subcutaneously into a leg of mice. After 2 hours (after intravenous injection) or 24 hours (after intravenous, subcutaneous injection and injection into a muscle) mice were euthanized by cervical dislocation. At first, measurements of a fluorescence spectra of blood, liver, spleen, lung, brain, kidney were made using fluorescence spectrometer. Results showed that there is no difference from control spectrums using different injection sites in any of the tissue and quantum dots were found only in the areas they were injected. Secondary, confocal images of histological samples were made in order to define quantum dot’s distribution in mice better. Also, we used hematoksilin-eosin stained samples to register images by using light microscope so as to define whether quantum dots were able to penetrate into cells or they were found in intercellular space. Results showed that quantum dots were found in cells of spleen after 2 hours of intravenous injection. There were no distribution of quantum dots in lungs, kidney, liver and brain in any of the experiments